Leflunomide Metabolite Test Cost & Procedure

Rheumatoid arthritis is treated with the medication leflunomide (Arava®). It works by blocking the body from creating the antibodies that cause the disease's symptoms. (inflammation, edema, stiffness, joint pain). Leflunomide is a prodrug, meaning that it is given to the patient in an inactive form that the liver then transforms into an active metabolite.

Clinical significance smackdown!

Leflunomide Metabolite: The immunosuppressant drug leflunomide is used to treat rheumatoid arthritis. Teriflunomide, the drug's active form, is quickly and thoroughly metabolized from leflunomide. Patients receiving the indicated daily dosages experienced steady state plasma values of up to 63,000 ng/mL. All women of reproductive potential who stop taking leflunomide and those who are getting treatment but want to get pregnant are advised to go through the cholestyramine medication elimination process. This approach includes two independent tests that are at least 14 days apart to confirm that the plasma concentration of teriflunomide is less than 20 ng/mL.

Cracking the test details code

Methodology Mass spectrometry and chromatography

Assessment Type

The characteristics of this test's analytical performance have been established by Quest Diagnostics. The FDA has not endorsed or cleared it. This test is used for clinical applications and has been validated in accordance with CLIA requirements.

Reference Set(s)

Patients who were taking daily doses of 5, 10, or 25 mg of leflunomide had mean steady state plasma concentrations of teriflunomide of 8,800, 18,000, and 63,000 ng/mL, respectively. It is advised that pregnant women who stop taking leflunomide treatment go through the cholestyramine medication elimination process. This approach involves confirming, through two distinct tests done at least 14 days apart, that the plasma concentration of teriflunomide is less than 20 ng/mL.

How to Improve Your Suitable Specimen Types

Plasma EDTA in serum

• 50 ul of plasma or serum, Li Hep.

Specimen Transport

• Usual

Sample preparation in a laboratory centrifuge and storage in a cold room with a toxicology box.

Time Required for Sample Preparation in a Centrifuge: 3 working days

4 oC Sample Stability

The specimen for this test must be obtained, processed, aliquoted, and refrigerated within 45–60 minutes of the specimen being obtained. Patients must be sent to a Dynacare Laboratory and Health Services Center for collection if they are unable to comply with these requirements. Never employ a gel barrier tube. Transfer serum to a transport tube after centrifuging it.

Transport and Storage: Keep chilled and ship chilled.

Notes

To ensure proper dosing, this test is intended for the therapeutic medication monitoring of teriflunomide/leflunomide levels. This test is not intended to track the disappearance of teriflunomide in teriflunomide-free women who are capable of having children. Eurofins provides access to this service. (Sanofi-Aventis kit)